From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: UK speeding ticket
Date: Fri, 30 Nov 2007 19:00:32 -0500
Message-ID: <om61l35h9nn043hcj4mki3r7o97e25nqks@4ax.com>

On Thu, 29 Nov 2007 22:47:09 -0500, "Tom J" <tomnews@earthlink.net> wrote:

>Allan F Damp wrote:
>> A friend sent the following message. It may be completely "urban
>> legend" but it does have a modern technology ring.

>http://www.snopes.com/horrors/techno/radar.asp
>This farce has been around for 8 years!! Why don't people check out
>this junk before posting??????????  The same thing is happening on
>both sides of the political debates - 1 false email after the other
>just full of outright lies!!!

What an ass.  Are you ill, Tom?  Off your meds?  You're about to surpass sill as the
ass of the group.  I bet you pissed yourself scampering to snopes, a site about as
reliable as wikipedia. You need to take a good hard look in the mirror and see if you
like what you see.

As the OP noted, the tale as told is undoubtedly false, but as with many such
stories, there is an underlayment of fact.

Several of the Soviet anti-air missiles operate on the X-band.  During the Vietnam
war, many pilots purchased off-the-shelf "fuzzbusters" and mounted them on the
canopies to alert them to incoming missiles.  This was before the planes were
equipped with suitable threat warning receivers (TWR).  There was a nice article
about this in Car and Driver magazine that prompted many folks including my dad to
buy a radar detector and send over there via the VFW.

Snopes is flat wrong about the characteristics of police radars.  Nothing new there.
I currently own 3 police radars, have owned many others, have analyzed the
performance of most of them and am certified in TN and GA as a traffic radar expert
witness.

70s era (undoubtedly when this story started) radars that used the 2K25 pencil
klystron tube as the microwave source emitted in the 1 watt range in front of a
fairly high gain dish.  While the effective range of the units were limited because
of primitive receivers, the signals could be received for tens of miles line of
sight.  Even 90's vintage radars emit in the 10s of mW and can be received over
several miles.  Atmospheric anomolies that caused ducting and refraction would
greatly extend that range at times.

While the emitted signal was nominally continuous wave, the signal was modulated by
ripple from the high voltage inverter in the control head.  This resulted in a signal
that sounded much like that of a Soviet anti-air targeting radar. (I've heard
recordings of the latter.)  It is quite probable that an early pre-digital signal
processing TWR would receive this police radar signal and alert.  The early units did
not present PPI information; instead only lighting a warning light and sounding a
tone.  More modern ones can develop PPI and differentiate signal types.  Some info:
http://www.fas.org/man/dod-101/sys/ac/equip/an-alr-69.htm

Later models of police radars such as my Kustom Signals HR-11 operate in pulse mode.
The emitted signal would look very "missile-ish" to a TWR.  The latest radars such as
the Stalker operate in a wide band "chatter" mode designed to defeat civilian radar
detectors. (it doesn't).  Again, similar to modern military radar signatures.  In
general, police radar technology has followed military radar by a decade or so.
Snopes' claims to the contrary are completely wrong.

Anti-radiation (HARM) missiles are designed to lock onto a radar signal and fly
toward it.  Early HARMs had only simple 4 quadrant receivers that required the
emitter to remain on during the entire flight.  By the end of Vietnam, HARMs had the
ability to compute a vector to the target and fly to it even if the signal is turned
off.  Since police radar operates in the same band as Soviet armaments and emits a
signal similar to its radar, it follows that a HARM missile could indeed seek to a
police radar.

That's the factual part.  Here's how I imagine the story got started.  Some fighter
jock somewhere in the US, undoubtedly on a training mission, has his TWR alarm to a
police radar.  He located the source of the microwaves and saw that it was a cop
running radar.  The pilot had fantasies of pickling off a HARM and blowing the cop
off the highway.  In lieu of actually doing that, he combined his training with a
little creativeness and made up that story.  Who knows?  It might even have gotten
written down and sent to some cop shop as a joke.

A somewhat similar real-life incident was reported via the Forest Service's Radio
Service network when I was moonlighting as a radio engineer.  An AP had set up his
police radar oriented such that it was line-of-sight with the base's main traffic
control radar.  There was sufficient harmonic energy in the beam to damage the police
radar's primitive receiver.  The FSRS back then offered its radio repair services to
small police departments.  The tech bulletin was sent out so that we'd know what to
look for if we received police radars in for repair that had mysterious receiver
failures.

John